Dispersion-stabilizing agent for inorganic powder in oily material

ABSTRACT

A dispersion stabilizing agent for inorganic powder in an oily material, comprising a copolymer of (i) a polyoxyalkylene derivative represented by the general formula [I] below with (ii) one or more of maleic acid and the derivatives thereof selected from the group of maleic anhydride, maleic acid, maleic acid salts, maleic acid amides, and maleic acid esters,    &lt;IMAGE&gt;  [I]  where Z is a residue of a compound having 2-8 hydroxyl groups, AO is an oxyalkylene group having 2-18 carbon atoms, R1 is an unsaturated hydrocarbon group having 2-5 carbon atoms, R2 is a hydrocarbon group having 1-40 carbon atoms, a=0 to 1000, b=0 to 1000, c=0 to 1000, l=1 to 8, m=0 to 2, n=0 to 7, (l+m+n)=2 to 8, (al+bm+cn)=1 to 1000, m/(l+n)&lt;/=1/2.

This is a continuation of application Ser. No. 07/442,762 filed Nov. 29,1989, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a dispersion-stabilizing agent forinorganic powder in an oily material. More particularly, the presentinvention relates to a dispersion-stabilizing agent for inorganic powderin an oily material, which can disperse an inorganic powder in an oilymaterial within a short period of time and can stabilize the dispersionover a long period of time.

2. Related Background Art

Dispersion of inorganic powder in an oily material are used in variousindustrial fields. A familiar example is a paint, in which a pigment anda filler are dispersed in a resin solution. Recently, dispersions ofinorganic powder in hydrocarbon oils have come to be used for abrasivesand fuel tank cleaning liquids.

In such a dispersion in oil, a dispersion-stabilizing agent is generallyemployed for dispersing an inorganic powder into the oil. U.S. Pat. No.4,354,872 discloses use of an alkanolamide, a fatty acid and magnesiumlauryl sulfate for dispersing magnesium oxide in hydrocarbon oil.

The dispersion-stabilizing agents are required to be capable ofdispersing the inorganic powder rapidly in an oily material within ashort period of time, and are required simultaneously to be capable ofstabilizing the inorganic powder without precipitating the inorganicpowder over a long period of time, and to be capable of easilyre-dispersing the inorganic powder even when it has precipitated.

Various dispersion-stabilizing agents have been reported to meet therequirements. However, none has satisfied simultaneously theabove-mentioned two requirements.

SUMMARY OF THE INVENTION

The object of the present invention is to provide adispersion-stabilizing agent for inorganic powder in an oily material,which satisfies the above-mentioned two requirements: namely, capabilityof dispersing inorganic powder rapidly in an oily material within ashort period of time, and capability of stabilizing the inorganic powderover a long period of time.

According to the present invention, there is provided a dispersionstabilizing agent for inorganic powder in an oily material, comprising acopolymer of (i) a polyoxyalkylene derivative represented by the generalformula [I] below and (ii) one or more of maleic acids and thederivatives thereof selected from the group of maleic anhydride, maleicacid, maleic acid salts, maleic acid amides, and maleic acid esters,##STR2## where Z is a residue of a compound having 2-8 hydroxyl groups,AO is an oxyalkylene group having 2-18 carbon atoms, R¹ is anunsaturated hydrocarbon group having 2-5 carbon atoms, R² is ahydrocarbon group having 1-40 carbon atoms, a=0 to 1000, b=0 to 1000,c=0 to 1000, l=1 to 8, m=0 to 2, n=0 to 7, (l+m+n)=2 to 8, (al+bm+cn)=1to 1000, and m/(l+n)≦1/2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The inventors of the present invention, after the comprehensive study toattain the above objects, have completed the present invention.

The dispersion-stabilizing agent of the present invention is a copolymerof (i) a polyoxyalkylene derivative represented by the general formula[I] shown above with (ii) one or more of maleic acid and its derivativesselected from the group of maleic anhydride, maleic acid, maleic acidsalts, maleic acid amides, and maleic acid esters, where thepolyoxyalkylene derivative unit and the maleic unit may respectively becomposed of one kind of units or a mixture of two or more kinds ofunits.

The ratio of the polyoxyalkylene derivative units to the maleic unitsused is preferably be from 7:3 to 3:7, more preferably approximately 1:1based on polymerizable double bond equivalence, but is not limitedthereto. The average molecular weight of the copolymer is preferablyfrom 1,000 to 2,000,000 in terms of weight average molecular weight, butis not limited thereto.

In the general formula [1], the compounds having 2-8 hydroxyl groups andcontaining Z as a residue include polyhydric alcohols such as ethyleneglycol, propylene glycol, butylene glycol, dodecylene glycol,octadecylene glycol, neopentyl glycol, styrene glycol, glycerol,diglycerol, polyglycerol, trimethylolethane, trimethylolpropane,1,3,5-pentanetriol, erythritol, pentaerythritol, dipentaerythritol,sorbitol, sorbitan, sorbide, a sorbitol-glycerol condensate, adonitol,arabitol, xylitol, and mannitol; polyhydric phenols such as catechol,resorcin, hydroquinone, and phloroglucin; saccharides such as xylose,arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose,sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, raffinose,gentianose, and melezitose; and partially etherfied compounds orpartially esterified compounds thereof.

The oxyalkylene groups denoted by AO having 2-18 carbons include anoxyethyelne group, an oxypropylene group, an oxybutylene group, anoxytetramethylene group, an oxystyrene group, an oxydodecylene group, anoxytetradecylene group, an oxyhexadecylene group, and an oxyoctadecylenegroup, the oxyalkylene group may be composed of one kind of units or amixed adduct of two or more kinds of units, and the mixed adduct may bea random adduct or a block adduct.

The unsaturated hydrocarbon groups denoted by R¹ having 2-5 carbonsinclude those having a polymerizable unsaturated bond such as a vinylgroup, an allyl group, a methallyl group, a 3-butenyl group, a4-pentenyl group, and a 3-methyl-3-butenyl group.

The hydrocarbon groups denoted by R² include those having 1-40 carbons,of which particularly those having 1-24 carbons are preferable,including methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl,amyl, isoamyl, hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, decyl,undecyl, dodecyl, isotridecyl, tetradecyl, hexadecyl, isohexadecyl,octadecyl, isooctadecyl, oleyl, octyldodecyl, docosyl, decyltetradecyl,benzyl, cresyl, butylphenyl, dibutylphenyl, octylphenyl, nonylphenyl,dodecylphenyl, dioctylphenyl, dinonylphenyl, styrenated phenyl, andnaphthyl.

The polyoxyalkylene derivative represented by the general formula [I]have at least one R¹. The carbon number of R¹ affects to thepolymerization reactivity: excessively long carbon chain of R¹ lowersthe reactivity of the derivative, the above-mentioned range of thecarbon number therefore being suitable. The derivative in which l,namely, the number of R¹, is 1 will give a linear copolymer, while thederivative in which l is 2 or more will give a crosslinked copolymer.The crosslinking degree can be adjusted by selecting the value of l toprepare a desired copolymer.

The value of (al+bm+cn) is limited to be not more than 1000, because thevalue exceeding 1000 is not easily attainable practically.

Regarding the relationship among l, m, and n, while m is defined to bein the range of from 0 to 2, an excessively high value of m relative to(l+n) is undesirable, because it causes gellation during the reaction togive a crosslinked ester which cannot be adjusted. Hence l, m, and nshould be in the relationship of m/(l+n)≦1/2.

The carbon number of AO may be selected arbitrarily from the range offrom 2 to 18. By combination of AO with R², the ratio of the hydrophilicgroup to the lipophilic group may be adjusted.

Of the maleic acid group copolymerizing with the polyoxyalkylenederivative of the general formula [I] the maleic acid salts include thesalts of ammonia; salts of monoamines such as methylamine, ethylamine,propylamine, butylamine, hexylamine, octylamine, 2-ethylhexylamine,nonylamine, decylamine, dodecylamine, isotridecylamine, tetradecylamine,hexadecylamine, isohexadecylamine, stearylamine, isostearylamine,oleylamine, linolamine, octyldodecylamine, docosylamine,decyltetradecylamine, and aniline; salts of polyamines such asethylenediamine, tetramethylenediamine, dodecylpropylenediamine,octadecylpropylenediamine, oleylpropylenediamine, diethylenetriamine,triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine;salts of alkanolamines such as monoethanolamine, diethanolamine,triethanolamine, monoisopropanolamine, diisopropanolamine,triisopropanolamine, adducts of alkylene oxide to the aforementionedmonoamines and polyamines; salts of amino acids such as lysine,arginine, and histidine; salts of alkali metals such as lithium, sodium,and potassium; and salts of alkaline earth metals such as magnesium, andcalcium.

The maleic acid amides include reaction products of amidation of maleicanhydride with the aforementioned salt-forming amines. The maleic acidesters include reaction products of esterification of maleic anhydrideor maleic acid with aliphatic, aromatic or alicyclic alcohols having1-22 carbon atoms. Specific examples of the alcohols are butanol,hexanol, decanol, tridecanol, octadecanol, benzyl alcohol, andcyclohexanol.

The polisher is easily prepared by copolymerizing a polyoxyalkylenederivative of the general formula [I] with a maleic acid or itsderivative in the presence of a radical initiator such as a peroxide. Inthe case where the maleic unit is other than maleic anhydride, apolyoxyalkylene derivative of the general formula [I] is preferablycopolymerized with maleic anhydride in the presence of a radicalinitiator, and the maleic anhydride moiety is then hydrolyzed to amaleic acid moiety, neutralized to form a salt, reacted with an amine toform an amide, or reacted with alcohol to form an ester, because suchprocedures will produce easily a high molecular product in a simplermanner.

In the copolymerization, another copolymerizable component such asstyrene, α-olefin, or vinyl acetate may be incorporated.

The copolymer thus prepared may vary properties thereof over a broadrange by changing suitably Z, AO, R¹, R², l, m, n, and the maleic unit.The copolymers soluble in an oily material in a certain limited degreewill be adsorbed better by an inorganic powder, giving favorableresults, in comparison with the copolymers freely soluble or completelyinsoluble in the oily material. By a certain kind of inorganic powder, acopolymer having remaining carboxylic group is adsorbed better. In casewhere the maleic unit is a maleic acid salt, a maleic acid amide, or amaleic acid ester, the copolymer with the carboxyl group having beenpartially reacted, preferably 50% equivalent or less is in many casespreferred in comparison with the one with the carboxyl group havingtotally reacted.

The inorganic powder to be dispersed in the present invention is notlimited, and the examples thereof are silicates such as kaolin (a whiteburning aluminum silicate), aluminum silicate, clay (a hydrated aluminumsilicate), talc (a natural hydrous magnesium silicate), mica (any ofseveral silicates of varying chemical compositions), asbestos powder (agroup of impure magnesium silicate minerals), calcium silicate,sericite, and bentonite (a colloidal clay (aluminum silicate));carbonates such as calcium carbonate, magnesium carbonate, bariumcarbonate, and dolomite (a carbonate of calcium and magnesium); sulfatessuch as calcium sulfate, and barium sulfate; metal oxides such asmagnesium oxide, alumina, antimony oxide, titanium oxide, white carbon(a colloidal silica), diatomaceous earth (a soft bulky solid materialwhich is 88% silica), and iron oxide; metal hydroxides such as aluminumhydroxide, magnesium hydroxide, calcium hydroxide, iron hydroxide, andmetatitanic acid; metal powders such as aluminum powder, copper powder,and nickel powder; and other various inorganic powders such as siliconcarbide, silicon nitride, boron nitride, zirconium oxide, bariumtitanate, satin white (a mixture of hydrated lime, potash alum, andaluminum sulfate), carbon black (finely divided forms of carbon), andgraphite (a crystalline allotropic form of carbon characterized by ahexagonal arrangement of the atoms).

Average particle sizes of the inorganic powder vary significantlydepending on the kind of the inorganic powder, but generally not morethan 100 μm, and nominally and preferably in the range approximatelyfrom 0.1 to 50 μm.

The oils as the dispersion medium for dispersing the above-mentionedinorganic powder are not limited. The examples thereof include fuel oilssuch as kerosene, gas oil, and heavy oil; aliphatic hydrocarbons such ashexane, cyclohexane, and isooctane; aromatic hydrocarbons such asbenzene, toluene, and xylene; ester oils such as ethyl acetate, dioctylphthalate, soybean oil, and linseed oil; halogenated hydrocarbons suchas 1,1,1-trichloroethane, trichloroethylene, and chlorodifluoromethane;liquid paraffin, liquid paint resin, liquid rubber, and so on.

The amount of the dispersion-stabilizing agent for an oily material tobe used in the present invention is from 0.05 to 10 parts by weight,preferably from 0.1 to 7 parts by weight based on 100 parts by weight ofthe inorganic powder. The amount of 0.05 part by weight or less isineffective, while the use of 10 parts by weight or more does notsignificantly enhance the effect, and is economically disadvantageous.

By employing the dispersion-stabilizing agent of the present invention,a dispersion of inorganic powder in oily material can be prepared in aconventional manner: for example, an inorganic powder is added to an oilcontaining the dissolved dispersion-stabilizing agent mentioned above,and the mixture is agitated.

In the present invention, the use of the specified copolymer ofpolyoxyalkylene derivative with a maleic unit as the effectiveingredient makes it possible to disperse inorganic powder rapidly in anoily material within a short period of time and to prepare a dispersionof inorganic powder in an oily material which is stable over a longperiod of time.

The examples below illustrate specifically the present invention. Thecompounds shown in Table 1 were used for the dispersion-stabilizingagents in the examples of the present invention and the comparativeexamples. In the Examples, all percents are by weight.

EXAMPLE 1

200 g of precipitated calcium carbonate powder having an averageparticle diameter of 0.5 μm was placed as an inorganic powder in a2-liter beaker. Thereto, 400 g of toluene was added which contains thedissolved dispersion-stabilizing agent in the indicated amount. Themixture was agitated with a 4-blade impeller at 120 rpm for 3 minutes,and then left to stand for 1 minute. The wettability, in the presence ofthe dispersion-stabilizing agent, of the precipitated calcium carbonateby toluene was evaluated from the state of the calcium carbonate powderremaining in the bottom of the beaker based on the four grades below.

1: The powder is entirely dispersed in the oil, and no powder remains atthe bottom.

2: The powder is almost entirely dispersed in the oil, but only a slightportion of the powder remains undispersed at the bottom.

3: Approximately half of the powder remain undispersed at the bottom.

4: Most of the powder remain at the bottom.

The dispersions rated as 1, 2, and 3, excluding those rated as 4respectively were violently agitated at 4,000 rpm for 5 minutes with anAutohomomixer (Type M, made by Tokushu Kika Kogyo K.K.), and thedispersion was transferred into a 500-ml measuring cylinder and left tostand for two days. Then a glass rod of 5 mm in diameter and 50 g inweight was allowed to fall through a guide provided on the upper portionof the measuring cylinder. The falling state was observed, and thedispersion stability was rated on two grades below:

1: The glass rod reaches the bottom of the cylinder.

2: The glass rod stops falling before reaching the bottom of thecylinder, a hard packed layer being formed.

The test results are shown in Table 2, which shows that the samplesemploying the dispersion-stabilizing agent of the present invention aresuperior in wettability and dispersion stability.

                                      TABLE 1                                     __________________________________________________________________________                                                              Weight-                                                  Maleic     Maleic    Average                                                  An-  Other Derivative                                                                              Molecu-                    Compound of General Formula I hydride                                                                            Monomer                                                                             (% equivalent                                                                           lar                 Sample No.                                                                           (mole)                        (mole)                                                                             (mole)                                                                              to carboxyl                                                                             Weight              __________________________________________________________________________    Example 1                                                                            CH.sub.2CHCH.sub.2 O(C.sub.2 H.sub.4 O).sub.5 C.sub.8 H.sub.17                                           1.0                                                                              1.0  --    --        34,000              Example 2                                                                            CH.sub.2CHCH.sub.2 O(C.sub.2 H.sub.4 O).sub.20 C.sub.18 H.sub.37                                         1.0                                                                              1.0  --    Dodecylamide                                                                         0.5                                                                              42,000              Example 3                                                                            CH.sub.2CHCH.sub.2 O(C.sub.3 H.sub.6 O).sub.3 (C.sub.2 H.sub.4                O).sub.3 CH.sub.3          1.0                                                                              1.0  --    Amide  0.5                                                                              11,000              Example 4                                                                             ##STR3##                  1.0                                                                              1.0  --    Octadecyl- amide                                                                     0.3                                                                              17,000              Example 5                                                                            CH.sub.2CHCH.sub.2 O(C.sub.2 H.sub.4 O).sub.8C.sub.6 H.sub.4C.sub.9            H.sub.19                  0.9                                                 ##STR4##                  0.1                                                                              1.0  --    --        22,500              Example 6                                                                            CH.sub.2CHCH.sub.2 OCH.sub.2 C[CH.sub.2 O(C.sub.3 H.sub.6 O).sub.3            (C.sub.2 H.sub.4 O).sub.10 CH.sub.3 ].sub.3                                                              0.9                                                                              1.0  Styrene                                                                             2-Ethylhexyl                                                                         0.4                                                                              66,000                                                        0.1   ether                         Example 7                                                                             ##STR5##                  0.9                                                                              1.0  --    Triethanol-                                                                          0.7                                                                              120,000                                                             amide salt                           CH.sub.2CHCH.sub.2 O(C.sub.3 H.sub.6 O).sub.30 (C.sub.2 H.sub.4               O).sub.70 CH.sub.2 CHCH.sub.2                                                                            0.05                                        Example 8                                                                             ##STR6##                  1.0                                                                              1.0  --    Calcium salt                                                                         0.5                                                                              33,400              Example 9                                                                            CH.sub.2CHCH.sub.2 O(C.sub.2 H.sub.4 O).sub.10 (C.sub.3 H.sub.6               O).sub.10 C.sub.18 H.sub.36                                                                              0.8                                                                              1.0  Meta- Dodecyl                                                                              0.2                                                                              77,000                                                        acrylic                                                                             ester                                                                   acid 0.2                                                                      Diglycerin                                                                    diallyl                                                                       ether 0.05                          Example 10                                                                            ##STR7##                  0.3                                                                              1.0  --    Cyclo- hexylamide                                                                    0.3                                                                              94,000                     CH.sub.2CHCH.sub.2 O(C.sub.3 H.sub.6 O).sub.20 (C.sub.2 H.sub.4               O).sub.10 C.sub.4 H.sub.9  0.7                                         Example 11                                                                            ##STR8##                  0.5                                                                              1.0  --    Na salt                                                                              0.45                                                                             9,900                       ##STR9##                  0.5                                         Comparative                                                                          Sorbitan monooleate                                                    Example 12                                                                    Comparative                                                                          Polyoxylethylene (10 moles)                                            Example 13                                                                           nonyl phenyl ether                                                     Comparative                                                                          Sodium bis-2-ethylhexylsulfo-                                          Example 14                                                                           succinate                                                              __________________________________________________________________________     Note:                                                                         *.sup.1) The group within the brackets { } is a random adduct.           

                  TABLE 2                                                         ______________________________________                                        Dispersion Stabilizing Agent                                                                            Amount                                                       Test    Sample   Used   Wetta-                                                                              Dispersion                             Remarks  No.     Number   (%)    bility                                                                              Stability                              ______________________________________                                        Invention                                                                              1       1        3.5    1     1                                      "        2       2        3.5    1     1                                      "        3       3        3.5    1     1                                      "        4       4        3.5    1     1                                      "        5       5        3.5    2     1                                      "        6       6        3.5    2     1                                      "        7       7        3.5    2     l                                      "        8       8        3.5    2     1                                      "        9       9        3.5    2     1                                      "        10      10       3.5    2     1                                      "        11      11       3.5    2     1                                      Comparison                                                                             12      12       3.5    2     2                                      "        13      13       3.5    3     2                                      "        14      14       3.5    3     2                                      "        15      none     0      4     .sup.  --.sup.1)                       ______________________________________                                         Note:                                                                         .sup.1) The dispersion stability test was not conducted.                 

EXAMPLE 2

A mixture of 100 g of alumina powder having an average particle diameterof 0.5 μm and 100 g of titanium oxide powder having a particle diameterof 0.8 μm was used as the inorganic powder. The tests were conducted byemploying a 500 g of gas oil containing the dissolveddispersion-stabilizing agent in the indicated amount relative to theweight of the inorganic powder in the same manner as in Example 1. Thetime period of standing for testing the dispersion stability was oneweek. The test results are shown in Table 3, which clearly shows thatthe samples employing the dispersion-stabilizing agent of the presentinvention are superior in wettability and dispersion stability.

                  TABLE 3                                                         ______________________________________                                        Dispersion Stabilizing Agent                                                                            Amount                                                       Test    Sample   Used   Wetta-                                                                              Dispersion                             Remarks  No.     Number   (%)    bility                                                                              Stability                              ______________________________________                                        Invention                                                                              16      1        4      2     1                                      "        17      3        4      l     1                                      "        18      5        4      l     1                                      "        19      7        4      2     1                                      "        20      9        4      2     1                                      "        21      11       4      2     1                                      Comparison                                                                             22      12       4      2     2                                      "        23      13       4      3     2                                      "        24      14       4      3     2                                      "        25      none     0      4     .sup.  --.sup.1)                       ______________________________________                                         Note:                                                                         .sup.1) The dispersion stability test was not conducted.                 

EXAMPLE 3

100 g of flaky graphite having an average particle diameter of 0.1 μmwas used as the inorganic powder. The tests were conducted by employing900 g of petroleum lubricant containing the dissolveddispersion-stabilizing agent in the indicated amount relative to theweight of the graphite, in the same manner as in Example 1. The timeperiod of standing for testing the dispersion stability was one month.The test results are shown in Table 4, which shows that the samplesemploying the dispersion-stabilizing agent of the present invention aresuperior in wettability and dispersion stability.

                  TABLE 4                                                         ______________________________________                                        Dispersion Stabilizing Agent                                                                            Amount                                                       Test    Sample   Used   Wetta-                                                                              Dispersion                             Remarks  No.     Number   (%)    bility                                                                              Stability                              ______________________________________                                        Invention                                                                              26      2        4      1     1                                      "        27      4        4      1     1                                      "        28      6        4      1     1                                      "        29      8        4      2     l                                      "        30      10       4      2     1                                      Comparison                                                                             31      12       4      3     2                                      "        32      13       4      3     2                                      "        33      14       4      3     2                                      "        34      none     0      3     2                                      ______________________________________                                    

EXAMPLE 4

200 g of carbon black having an average particle diameter of 0.05 μm asthe inorganic powder was added to a mixture of 200 g ofstyrene-butadiene copolymerized oil-extended rubber (SBR #1712) and 200g of a process oil containing the dissolved dispersion-stabilizing agentin the indicated amount relative to the carbon black. The mixture wasmilled for 5 minutes with a Banbury mixer. The mixture was then placedin a 100-ml measuring cylinder. The amount of the supernatant liquid wasmeasured after one day and seven days. The results are shown in Table 5,which demonstrates that the samples employing the dispersion-stabilizingagent of the present invention separates less supernatant liquid, and issuperior in dispersion stability.

                  TABLE 5                                                         ______________________________________                                        Dispersion Stabilizing Agent                                                                  Amount  Supernatant (ml)                                                Test   Sample   Used    One Day                                                                              7 Days                               Remarks   No.    Number   (%)     After  After                                ______________________________________                                        Invention 35     1        5       1.5    3.4                                  "         34     2        5       1.5    3.0                                  "         37     3        5       2.0    3.5                                  "         38     4        5       2.4    4.0                                  "         39     6        5       1.8    2.4                                  "         40     7        5       1.4    3.4                                  "         41     9        5       1.2    4.2                                  "         42     10       5       1.8    4.1                                  Comparison                                                                              43     12       5       20.4   35.4                                 "         44     13       5       22.2   33.4                                 "         45     14       5       19.4   30.0                                 "         46     none     0       20.4   30.3                                 ______________________________________                                    

EXAMPLE 5

100 g of aluminum powder having an average particle diameter of 1 μm asthe inorganic powder was added to 400 g of an unsaturated polyesterresin (Polylight: TP-210, made by Dainippon Ink and Chemicals, Inc.)containing the dissolved dispersion-stabilizing agent in the indicatedamount relative to the aluminum powder. The mixture was agitated at 2000rpm for 5 minutes with a homogenizer to prepare a dispersion. 100 ml ofthe dispersion was transferred into a 100-ml measuring cylinder and leftto stand. After 14 days, the volume of the supernatant layer and theformation of hard pack were observed. The results are shown in Table 6,which demonstrates that samples employing the dispersion-stabilizingagent of the present invention give less supernatant layer and does notform a hard pack, thus being superior in dispersion stability.

                  TABLE 6                                                         ______________________________________                                        Dispersion Stabilizing Agent                                                                Amount 14 Days After                                                     Test   Num-    Used   Superna-                                                                             Formation of                            Remarks  No.    ber     (%)    tant (ml)                                                                            Hard Pack                               ______________________________________                                        Invention                                                                              47     1       10     8.5    no                                      "        48     3       10     7.8    no                                      "        49     5       10     7.9    no                                      "        50     7       10     6.6    no                                      "        51     9       10     7.0    no                                      Comparison                                                                             52     12      10     35.5   yes                                     "        53     14      10     40.7   yes                                     "        54     none     0     58.9   yes                                     ______________________________________                                    

While the invention has been described in detail and with reference tospecific embodiment thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A liquid composition consisting of an inorganicpowder, an oil, said inorganic powder being compatible with said oil,and a polymer component which is a vinyl copolymer of (i) apolyoxyalkylene derivative represented by the general formula (I) belowwith (ii) one or more of maleic acid and the derivatives thereofselected from the group consisting of maleic anhydride, maleic acid,maleic acid salts, maleic acid amides, and maleic acid esters, ##STR10##where Z is a residue of a compound having 2-8 hydroxyl groups, AO is anoxyalkylene group having 2-18 carbon atoms, R¹ is an unsaturatedhydrocarbon group having 2-5 carbon atoms, R² is a hydrocarbon grouphaving 1-40 carbon atoms, a=0 to 1000, b=0 to 1000, c=0 to 1000, l=1 to8, m=0 to 2, n=0 to 7, (l+m+n)=2 to 8, (al+bm+cn)=1 to 1000,m/(l+n)≦1/2.
 2. The composition as in claim 1, wherein the inorganicpowder is selected from the group consisting of aluminum silicate,magnesium silicate, calcium silicate, calcium carbonate, magnesiumcarbonate, barium carbonate, calcium magnesium carbonate, calciumsulfate, barium sulfate, calcium potassium aluminum sulfate, magnesiumoxide, alumina, antimony oxide, titanium oxide, silicon oxide, ironoxide, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, ironhydroxide, metatitanic acid, aluminum powder, copper powder, nickelpowder, silicon carbide, silicon nitride, boron nitride, zirconiumoxide, barium titanate, carbon black and graphite.
 3. The composition asin claim 1, wherein the oil is selected from the group consisting ofkerosene, gas oil, heavy oil, hexane, cyclohexane, isooctane, benzene,toluene, xylene, ethyl acetate, dioctyl phthalate, soybean oil, linseedoil, 1,1,1-trichloroethane, trichloroethylene, chlorodifluoromethane anda liquid paraffin.
 4. The composition as in claim 1, wherein the amountof the vinyl copolymer is from 0.05 to 10 parts by weight based on 100parts by weight of the inorganic powder.